1. Field of the Invention
The present invention relates to ball joint assemblies, and more particularly to a structure of a flanged ball rod for a spherical joint assembly for steering and suspension systems of automotive vehicles.
2. Description of the Prior Art
Ball joint assemblies of steering and suspension systems of automotive vehicles are well known in the prior art. Typically, the ball joint assembly comprises a casing defining a cavity having a cylindrical or spherical form, a bearing member disposed within the casing, and a ball pin having a ball portion slidably supported within the bearing member. The ball joint assemblies are used to mechanically couple two components of the vehicle steering and suspension systems. One of the components is secured to the casing of the ball joint assembly, while the other components is secured to the ball rod, thus providing the angular and rotational movement therebetween.
The typical ball pin has a substantially spherical head member at its one end and an elongated substantially cylindrical shank member at its other end. The head portion of the ball rod is coupled to the single or divided bearing member and is housed within the cavity of the ball joint casing. The shank member of the ball pin is provided with an integrally formed annular flange member. The flange of the ball pin is responsible for providing the adequate condition for positioning and securing of the components of the steering or suspension system to be pivotally coupled.
The flanged ball pins are typically manufactured by metal forming, such as forging, or machining from metallic materials, as an integral single-piece part. However, this requires the use of expensive steel alloys of superior grade providing necessary strength and deformability, thus increasing manufacturing cost of the ball joint assembly. Moreover, there is the need of more rigorous manufacturing cares, because of the accumulation of areas subject to mechanical stresses (cracks).
The present invention provides a novel arrangement of a ball joint assembly for use in a motor vehicle, and a method for manufacturing thereof.
The spherical joint assembly in accordance with the present invention comprises a ball pin, a bearing receiving a ball portion of the ball pin, a casing housing the bearing, and a protective cap having a first end secured to the casing and a second end mounted about a shank member of the ball pin. The ball pin of the present invention includes two separate pieces: a single-piece ball rod having a spherical ball portion at its one end and an elongated substantially cylindrical shank member at its other end, and a separately manufactured annular flange member selectively positioned over the shank member of the ball rod and secured thereto by interference (press) fitting.
Preferably, the shank member of the ball rod is provided with an integral stop flange for accurate positioning of the flange member on the shank member.
In accordance with the first embodiment of the ball pin of the present invention, a front face of the flange member facing the ball member of the ball pin, has generally frusto-conical surface that allows its application in ball joints that demand greater angular movement, without a flange edge damaging the protective cap provided on the ball joint assembly. Alternatively, in accordance with the second embodiment of the ball pin of the present invention, the flange member has flat and substantially parallel opposite faces.
A novel method for manufacturing the ball pin in accordance with the present invention is preformed in the following manner: first, the ball rod is formed, preferably by metal deforming, and the annular flange member is manufactured. Then, the flange member is mounted over the shank member of the ball rod. Finally, the flange member is secured about the shank member by interference fit.
Therefore, the ball joint assembly in accordance with the present invention, and a method for manufacturing thereof, represent an improved arrangement that allows greater dimensional accuracy and considerable reduction of the manufacturing cost, as it simplifies the design, increases the working life of the metal forming tools and, considerably decreases the loss of material in the process and contributes to the preservation of the environment, providing saving of electric energy.